Dual plane breast implant

ABSTRACT

A soft breast prosthesis is provided, the prosthesis having a surface configuration advantageous for dual plane placement of the prosthesis in a breast.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/728,249 filed on Jun. 2, 2015, which is a continuation of U.S. patentapplication Ser. No. 13/908,232 filed Jun. 3, 2013, which claimspriority to U.S. Provisional Patent Application No. 61/655,937, filedJun. 5, 2012, and which U.S. patent application Ser. No. 13/908,232 is acontinuation-in-part of U.S. patent application Ser. No. 12/540,317,filed Aug. 12, 2009 which claims priority to U.S. Provisional PatentApplication No. 61/088,418, filed Aug. 13, 2008, the entire contents ofeach of these documents being incorporated herein by this reference.

FIELD OF THE INVENTION

The present invention relates to soft prosthetic implants and, moreparticularly, to textured exterior surfaces of such implants, forinstance, breast implants.

BACKGROUND OF THE INVENTION

Implantable prostheses are commonly used to replace or augment bodytissue. In the case of breast cancer, it is sometimes necessary toremove some or all of the mammary gland and surrounding tissue, whichcreates a void that can be filled with an implantable prosthesis. Theimplant serves to support surrounding tissue and to maintain theappearance of the body. The restoration of the normal appearance of thebody has a beneficial psychological effect on post-operative patients,eliminating much of the shock and depression that often followsextensive surgical procedures. Implantable prostheses are also used moregenerally for restoring the normal appearance of soft tissue in variousareas of the body, such as the buttocks, chin, calf, etc.

Soft implantable prostheses typically include a relatively thin andflexible envelope or shell made of vulcanized (cured) siliconeelastomer. The shell is filled either with a silicone gel or with anormal saline solution. The filling of the shell takes place before orafter the shell is inserted through an incision in the patient.

In the United States, women can generally choose between two differenttypes of breast implant shell surfaces: a smooth surface and a texturedsurface. The surgeon generally recommends the type of surface based onhis or her technique and the need of the individual patient.

Breast implants may be placed in the breast in one of several differentpositions, depending on desired outcome, and/or patient and surgeonpreference.

In subglandular placement, the breast implant is placed in a surgicallyformed pocket directly between the glandular breast tissue and thepectoralis major muscle. This placement most approximates the plane ofnormal breast tissue. In addition, this placement may offer shortersurgery, less pain and discomfort and perhaps a faster recovery. On thedownside, subglandular placement may result in a more palpable implant,a higher chance of visible rippling or folding of the implant, andhigher risk of capsular contracture.

In submuscular placement, the breast implant is placed beneath thepectoralis major muscle. Thus, the implant is further away from the skinsurface and may be less visible or less palpable. This placement mayappear more “natural” because the implant is further away from the skin.It may require a longer surgery and recovery period, but is believed toresults in a reduced chance for capsular contracture. In breastreconstruction patients where natural breast tissue may be substantiallyor entirely absent, this placement approach effects maximal coverage ofthe implant.

Dual plane breast implant placement is a combination approach in whichthe implant is placed beneath the pectoralis major muscle, after thesurgeon releases the inferior muscular attachments. As a result, theupper portion of the implant is partially beneath the pectoralis majormuscle, while the lower portion of the implant is positioned in thesubglandular plane. This implantation technique may achieve improvedcoverage of the upper portion of the implant and allow filling of minorlaxity of the lower breast.

Despite many advances in the development of safe and comfortable breastprostheses, there remains room for improvement.

SUMMARY OF THE INVENTION

The present invention provides a prosthesis suitable for implantation ina human being, for example, a breast implant suitable for use inreconstruction or augmentation of the human breast. The prosthesisgenerally comprises an implantable member, for example, an elastomericshell that is filled or is fillable with a liquid or gel. Theimplantable member has an exterior surface including one or morefixation regions defined thereon and configured, positioned orstructured to provide enhanced or controlled tissue ingrowth oradhesion.

In accordance with one aspect of the invention, the fixation surfacesare discrete, generally elongated surface portions extending across ananterior face or a posterior face of the implant. These fixationsurfaces, sometimes herein referred to as “fixation regions”, aregenerally defined by a texture, roughness or sheen that is differentfrom a texture, roughness or sheen of adjacent surface portions of theimplant.

In some embodiments, the fixation regions have an increased or enhancedtexture relative to the balance of the anterior face or posterior faceof the implant. In other words, the balance of the exterior surface maybe relatively less textured than the fixation regions. In someembodiments, the fixation regions are textured and adjacent surfaces,for example, the surface or surfaces that are not defined by thefixation regions, are substantially less textured, or are relativelysmooth.

The prosthesis may be structured to encourage enhanced tissue ingrowthor adhesion at the fixation regions, relative to an otherwise identicalsurface without such texture, roughness or sheen.

In one aspect of the invention, the fixation regions are positionedand/or configured such that the prosthesis, after implantation in thebody, moves more naturally with the human body, for example, in relativeunity with the muscles of the body. It is contemplated that because theimplant moves more naturally with the human body, the implant may beless prone to wear resulting from material stresses relative toconventional implants, for example, implants without such fixationregions. Furthermore, it is contemplated that the present implants willbe more comfortable to the patient in that they will move more naturallywith the body.

In a more specific aspect of the invention, the fixation regions may belocated at specific regions on an anterior face of the shell, that is, aface of the shell which faces the front of the human body when theimplant has been appropriately implanted in the human body.Alternatively or additionally, one or more discrete fixation surface maybe provided on a periphery of the shell (e.g. circumferentially) and/oron the posterior face of the shell, that is, the face of the shell thatfaces the back of the human body when the implant has been implanted inthe human body.

In an even more specific aspect of the invention, the fixation regionscomprise at least one elongated region located on the anterior face ofthe shell. The at least one elongated region may be, for example, aband-shaped region or alternatively, a plurality of band shaped regionshaving enhanced texture, roughness or sheen.

The elongated fixation regions may be positioned to align with one ofthe pectoralis major muscle groups or pectoralis minor muscle groups ofthe human body when the implant is implanted in the body. For example,in one embodiment of the invention, the at least one elongated regioncomprises a diagonally positioned band shaped region intended to alignwith the pectoralis major muscle group when the implant has beenimplanted in the body. In another embodiment, the at least one fixationregion comprises a plurality of elongated regions in a radiatingconfiguration generally copying the positioning of the pectoralis minormuscle group wherein the implant has been implanted in the body.

In another broad aspect of the invention, the prosthesis comprises abreast implant having a shell including a fixation region having a firsttexture and a balance of the shell surface having a second texture thatis different from the first texture. In other words, in some embodimentsof the invention, the entire, or substantially entire, exterior of thebreast implant shell is a textured surface with specific regions thereofhaving a greater degree of texturing relative to the remaining portionsof the textured surface.

It is contemplated that such different texturing will stimulate orencourage different degrees of tissue ingrowth or adhesion at thedifferent fixation regions. For example, in one embodiment, the firstfixation region is located on a posterior face of the implant and thesecond fixation region is located on an anterior face of the implant.The first fixation region may be defined by a texture that is moreconducive to tissue interaction and adhesion whereas the second fixationregion may be defined by a texture that is relatively less conducive totissue interaction and adhesion.

In one embodiment, a breast prosthesis is provided having a relativelymore significant texture defining the anterior surface of the implant,and a less textured or smooth surface defining the posterior surface ofthe implant.

In yet another aspect of the invention, the prosthesis comprises a shellhaving an exterior structured to contact tissue, the shell including afirst fixation surface having a first open cell structure, and a secondfixation surface having a second open cell structure different than saidfirst open cell structure. In addition, the first fixation surface andthe second fixation surface are positioned to encourage respectivelydifferent degrees of tissue ingrowth or tissue adhesion by the body at abody-shell interface.

For example, the first open cell structure comprises relatively largeopen cells and the second open cell structure comprises relativelysmaller open cells. Alternatively or additionally, the first open cellstructure may comprise a first distribution of cells and the second opencell structure comprises a second distribution of cells wherein thefirst distribution of cells is relatively more dense than the seconddistribution of cells.

In yet another specific aspect of the invention, the first open cellstructure comprises relatively large rounded open cells and the secondopen cell structure comprises relatively small rounded open cells.Alternatively, the first open cell structure comprises relativelyrounded open cells and the second open cell structure comprisesrelatively angular open cells.

Advantageously, in accordance with certain embodiments, the first andsecond fixation surfaces are positioned and structured to be at leastsomewhat effective to disrupt or disorient capsular tissue formationabout the prosthesis after the prosthesis has been implanted in thebody.

The present invention further provides a breast prosthesis shell forimplantation in a human being, the shell manufactured by the steps ofproviding a shell precursor; applying a layer of silicone elastomer tothe shell precursor, applying solid particles of a first configurationto a portion of the layer of silicone elastomer and applying solidparticles of a second configuration to another portion of the layer ofsilicone elastomer before the layer is fully cured. After the layerincluding the solid particles embedded therein is cured, the solidparticles are then dissolved, for example, by means of a solvent thatdoes not dissolve the silicone elastomer to any appreciable extent. Theresulting elastomer shell includes a first open cell texture regionformed by said application of the solid particles of the firstconfiguration, and a second open cell texture region formed by saidapplication of the solid particles of the second configuration.

In yet another aspect of the invention, a method of augmenting orreconstructing a breast of a human being is provided. The methodgenerally comprises providing an implantable member including at leastone elongated fixation region as described elsewhere herein andimplanting the implantable member into a breast of a human being suchthat the fixation region generally aligns with one of the pectoralismajor muscle group and the pectoralis minor muscle group. The method mayfurther comprise filling the implantable member with a liquid or gelprior to or after the implanting step.

In another aspect of the invention, a dual plane breast prosthesis isprovided, the prosthesis comprising an implantable member including anexterior defined by a textured lower region or lower pole, configuredfor subglandular placement, and an upper region or upper pole, that issmooth or differently textured and which is configured for submuscularplacement. For example, the first texture and the second texture arestructured such that first texture encourages greater tissue ingrowththan the second texture.

In this embodiment, the implant may be surgically positioned as a dualplane breast implant, in other words, the implant may be placed in thebreast such that an upper portion of the implant is beneath thepectoralis major muscle, while the lower portion of the implant is inthe subglandular plane.

For example, the textured lower region may be a relatively moreaggressive textured surface that encourages adhesion and tissueingrowth, for example, to glandular and fatty tissue, while the upperregion may be a less aggressive textured surface, or even a smooth,untextured surface, to allow for more free muscle movement and reducedtissue adhesion.

The textured lower region may encompass between about 20% and about 80%of the surface area of the exterior of the implantable member, orbetween about 30% and about 70% of the surface area of the exterior ofthe implantable member, or between about 40% and about 60% of thesurface area of the exterior of the implantable member, or about 50% ofthe surface area of the exterior of the implantable member.

For example, the first texture may comprise an open cell texturedsurface and the second texture may be a closed cell textured surface.Alternatively, the first texture may comprise a closed cell texturedsurface and the second texture may be a relatively smooth, untexturedsurface. Other variations are contemplated.

The present invention further provides methods of augmenting orreconstructing a human breast using a dual plane approach wherein themethod comprises implanting in a breast, an implantable member includingan exterior defined by a lower surface region encompassing a lowerportion of the implantable member and an upper surface regionencompassing an upper portion of the implantable member, and wherein thelower surface region is defined by a first textured surface and theupper surface region is defined by one of a smooth surface or a secondtextured surface different from the first textured surface, and furtherthe implant being placed in the breast such that the upper surfaceregion is positioned between beneath the pectoralis major muscle and thelower region is positioned anteriorly of the pectoralis major muscle.

A further understanding of the nature and advantages of the presentinvention are set forth in the following description and claims,particularly when considered in conjunction with the accompanyingdrawings in which like parts bear like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become appreciatedas the same become better understood with reference to thespecification, claims, and appended drawings wherein:

FIGS. 1A-1B are a front view and a side elevational view, respectively,of an exemplary round breast implant of the present invention;

FIGS. 2A-2B are a front view and side elevational view, respectively, ofan exemplary shaped breast implant of the present invention;

FIGS. 3A and 3B are schematic views of a woman's upper torso showing,alignment of the pectoralis major muscle group and the pectoralis minormuscle group, respectively;

FIGS. 4A, 4B and 4C are vertical sectional views through a woman'sbreast and adjacent chest anatomy showing, respectively: subglandular,submuscular and dual plane placement of a breast implant of the presentinvention;

FIGS. 5A-5B are front and side elevational views of an exemplary roundbreast implant of the present invention having a generally elongated orband-shaped fixation surface;

FIGS. 6A-6B are front and side elevational views of an exemplary shapedbreast implant of the present invention having a generally elongated orband-shaped fixation surface;

FIG. 7 is a front elevational view of another breast implant inaccordance with the invention including a first fixation region having afirst texture and a second fixation region having a second texturedifferent from the first texture.

FIGS. 8A and 8B are front and rear elevational views of an exemplaryround breast implant of the present invention having a front texture anda rear texture that are different from one another.

FIG. 9A shows a simplified representation of a dual plane breast implantin accordance with one embodiment of the invention, the implant beingshown with an upper region located partially under the pectoralis majormuscle and a lower region located in the subglandular plane.

FIGS. 9B and 9C show a front view and side view, respectively, of a dualplane breast implant in accordance with an embodiment of the invention.

FIGS. 10A and 10B show another embodiment of the invention wherein theimplant includes a more textured anterior surface and a less textured orsmooth posterior surface.

DETAILED DESCRIPTION

The present invention provides a saline- or gel-filled soft implantshell, preferably a silicone elastomer shell, with a fixation surfaceover an exterior portion. The primary application for such soft implantsis to reconstruct or augment the female breast. Other potentialapplications are implants for the buttocks, testes, or calf, among otherareas.

The terms “fixation surface” or “fixation region”, as used herein,generally refer to a region or portion of an exterior surface of animplant which is positioned, structured or adapted to encourage tissueingrowth or adhesion at a body/implant interface. For example, afixation region may be a texture, roughness or sheen that is distinctfrom, for example, more pronounced than, adjacent surfaces of theimplant which do not encourage tissue ingrowth of adhesion to the samedegree as the fixation region. For example, other regions or surfaces ofthe implant exterior may be relatively smooth or less textured relativeto the fixation regions.

Such a fixation region may be formed by any suitable means, for example,but not limited to, a salt removal process such as described in U.S.Pat. No. 5,007,929, with appropriate changes being made. Alternatively,the fixation surfaces may be formed by separate textured elements suchas textured patches or films adhered to the outside of an otherwise“smooth” or less textured implant. Still, another method for forming thediscrete fixation regions may be by using a relatively roughened surfaceportion of a mold used to form the implant. Another method for formingthe present fixation regions includes texturing the exterior of theimplant after formation. The present invention should not be consideredlimited to any particular type of texturing or fixation surface, thoughthere might be certain advantages with one or more of these techniques.

Turning now to the Figures, FIGS. 1A and 1B are front and sideelevational views of an exemplary round breast implant 20 of the presentinvention. Generally, the implant 20 comprises an exterior surfacedefined by a relatively smooth anterior face 21, a textured posteriorface 22 and a textured peripheral region 24 located between the anteriorface 21 and the posterior face 22. The relatively smooth anterior facemay be a relatively less textured surface (relative to texture ofposterior face 22), such as, for example, a fine textured surface oreven a matte finish. In some embodiments, the implant 20 has arelatively smooth posterior face, a textured anterior face and atextured or smooth peripheral region. The fixation surfaces 22, 24themselves may have differing degrees of texturing. The diameter D andfront-to-back thickness T of the implant are shown and vary depending onthe patient's chest size and aesthetic considerations.

In the shown embodiment, the rear fixation surface 22 extends to theapex 26 or generatrix of the convex outer periphery of the implant 20.The peripheral fixation surface 24 continues forward a short distance Sonto the anterior or front surface 21. In some embodiments, the distanceS is between about 10% and about 30% of the thickness T. In someembodiments, the peripheral fixation surface 24 extends substantiallyentirely around the periphery of the implant 20, such that the implant20 is axi-symmetric. In other embodiments, the peripheral fixationsurface 24 may be abbreviated so as to extend around only a portion ofthe periphery of the implant, such as the inferior or superior half, orthe peripheral fixation surface may be broken up into spaced apartsegments. In some embodiments, the peripheral fixation surface 24comprises substantially evenly spaced segments resulting in alternatingsmooth and textured areas.

FIGS. 2A-2B illustrate an exemplary shaped breast implant 30 of thepresent invention having an inferior frontal lobe 32 simulating anatural breast. Like implant 20, implant 30 includes a rear fixationsurface 34 and a peripheral fixation surface 36. The width W, height H,and front-to-back thickness T of the implant are shown. If the frontprojection is round, then W=H, otherwise W may be greater than or lessthan H. When provided with a natural shape, the implant 30 has a properorientation, namely with the inferior lobe 32 at the lower center.Accordingly, the peripheral fixation surface 36 may extend completelyaround the periphery of the implant, or may be formed in discrete areasand be oriented relative to the natural shape of the implant. Forexample, the peripheral fixation surface 36 may be formed only aroundthe inferior or lower half of the implant, or may be formed only on thesides.

FIG. 3A illustrates a woman's upper torso schematically showing on oneside placement and alignment of the pectoralis major muscle group, whileFIG. 3B illustrates the placement and alignment of the pectoralis minormuscle group. These two muscle groups overlap one another and extendgenerally from the shoulder or collarbone region to the rib cageunderneath the breast. One aspect of the present invention is to providean implant including fixation surfaces such as described elsewhereherein, which are substantially aligned with these muscle groups whenthe implant is placed in the body.

While not wishing to be bound by any specific theory of operation, theregions or lines of contact of the implant with the primary chestmuscles experience greater movement than other areas of the implant notinterfacing the muscles. It is believed by the present inventors that byproviding a fixation region of the implant that is substantiallycoincident with or in substantial alignment with one or more of thesemuscle groups is more likely to remain secured and move with the muscle.In addition, it is contemplated that such discrete fixation regions mayprovide the benefit of disrupting capsule formation and/or reducing thepotential for capsular contraction.

FIG. 4A is a vertical sectional view through a woman's breast andadjacent chest anatomy showing a subglandular placement of a breastimplant 40. The implant 40 is positioned over the top of the pectoralismajor muscle group 42, which in turn overlays the pectoralis minormuscle group 44. The chest wall 48 showing a plurality of ribs 50 isalso indicated underneath the pectoralis minor muscle 44.

FIG. 4B shows a complete submuscular placement of an implant. In thiscase, the upper pole, for example, about ⅔ of the upper surface of thebreast implant is covered by the pectoralis muscle, and the lower pole,for example, about ⅓ of the lower portion of the breast implant, iscovered by the muscle fascia.

FIG. 4C shows a dual plane placement of the implant 40. With a dualplane placement, an upper pole of the implant is partially beneath thepectoralis major muscle, while a lower pole of the implant is located inthe subglandular plane. This may be accomplished by creating a pocketbeneath the pectoralis major muscle with release of the inferiormuscular attachments, with or without partial dissection of thesubglandular plane.

Each of these implant placements are utilized primarily depending on thesurgeon's clinical determination, sometimes influenced by a dialoguebetween patient and the surgeon and desired outcome. Depending on theimplant placements, the implant 40 may be in contact with one or bothmuscle groups. In some embodiments of the invention, the implantincludes substantially elongated fixation regions as described and shownherein, and said fixation regions being in substantial alignment withthe appropriate muscle group which interface the implant when theimplant is placed in the body.

For example, FIGS. 5A-5B are front and side elevational views of anexemplary round breast implant 60 of the present invention having aposterior face 62, a peripheral region 64, and an anterior faceincluding an elongated or band-shaped fixation region 66. Theband-shaped fixation region 66 extends generally along a diagonal angleand commences at the front border of the peripheral fixation surface 64.The illustrated embodiment, the fixation region 66 has a substantiallyconstant width W as seen from the front in FIG. 5A. In one embodiment,the width W is between about 1 mm to about 20 mm, for example, betweenabout 2 mm to about 15 mm. Alternatively, although not shown, thefixation region 66 may have a configuration that is other than aconstant width.

In one embodiment, the band-shaped fixation surface 66 is generallyoriented or aligned with either the pectoralis major muscle group orpectoralis minor muscle group when the implant is implanted in thebreast. For instance, if the implant 60 is destined for a submuscularplacement such as in FIG. 4B, the fixation surface 66 may be oriented tobe generally aligned with the pectoralis major muscle group, as seen inFIG. 3A. Alternatively, the angle at which the insertion surface 66 isoriented may be an approximation of the average angle of the pectoralismajor and pectoralis minor muscle groups. In this way, the implant 60has a fixation surface 66 to encourage tissue ingrowth or adhesion alongthe major stress lines of the implant. Preferably, the fixation surface66 is angled between about 30-60° with respect to a vertical planethrough the implant 60. Of course, if the implant 60 is round as shown,the fixation surface 66 itself defines the orientation thereof. In oneembodiment, the band-shaped fixation surface 66 is centered about thecenter of the implant 60, therefore creating two symmetric orientationsabout 180° apart. This arrangement facilitates implant by providing twopossible orientations for the surgeon.

The band-shaped fixation region 66 may extend substantially across theanterior face of the implant and may be defined by a texture that isdifferent from a balance of the anterior face. The fixation region 66may also have a different texture, for example, a more pronounced ormore aggressive texture, than the rear fixation surface 62 or peripheralsurface 64.

FIGS. 6A-6B illustrate another exemplary shaped breast implant 70 of thepresent invention. The implant 70 again features a rear fixation surface72, a peripheral fixation surface 74, and a plurality of separateband-shaped fixation surfaces 76 a, 76 b, and 76 c. These discretefixation surfaces 76 a, 76 b, 76 c are positioned or configured to alignwith one or more of the muscle groups described above. For example, thethree fixation surfaces 76 a, 76 b, 76 c may be generally orientedrelative to the fan-shaped pectoralis minor muscle group. Because theshaped implant 70 is orientation-specific, proper placement of theimplant orients the fixation surfaces 76 a, 76 b, and 76 c with theparticular muscle group. As mentioned above, the various fixationsurfaces 72, 74, 76 a, 76 b, and 76 c may be formed with a similar levelof roughness, or some may be less textured, such as with a matte finish.For instance, the rear and peripheral fixation surfaces 72, 74 may havea fine, matte finish, while the frontal fixation surfaces 76 a, 76 b, 76c are more densely textured. The present invention contemplates allpermutations of texturing choices.

In cross-section, the textured implant shells of the present inventionmay be single- or multi-layered. The overall thickness of the texturedimplant shell wall may be somewhat greater than a similar smooth-walledshell because of the extra layers of texture.

Turning now to FIG. 7, an anterior (front) view of another breastimplant of the present invention is shown generally at 110. The implant110 includes a shell 112 having an exterior surface including a firstfixation region 114 having a first texture 116 and a second fixationregion 118 having a second texture 122 that is different from the firsttexture 116. In the shown embodiment, the first texture 116 is a more“aggressive” texture than the second texture 122. The first texture 116is structured to encourage a greater degree of tissue interaction thanthe second texture 122.

In lieu of the second texture 122, it is contemplated that the secondfixation region 118, and perhaps the entire balance of the exterior ofthe shell 112, may be a low sheen surface, for example, a matte finish.

Turning now to FIGS. 8A and 8B, anterior (front) and posterior (rear)views, respectively, of another breast implant in accordance with theinvention are shown generally at 210. The implant 210 includes a shell212 having an anterior face 212 a and a posterior face 212 b, andincluding a first fixation region 214 having a first texture 216 and asecond fixation region 218 having a second texture 222 that is differentfrom the first texture 216. In the shown embodiment, the first texture216 may encompass the entire, or substantially entire, anterior face 212a of the implant 210. The first texture 216 is defined by a firstdistribution of pores, crevices or caverns that is relatively less densethan that of the second texture 222. The second texture 222, which mayencompass the entire, or substantially entire, posterior face 221 b ofthe implant 210, may be structured to encourage a greater degree oftissue interaction and adhesion than that of the first texture 216.

The shells 112 and 212 may be manufactured by a method of the inventioncomprising the steps of providing a shell precursor; applying a layer ofsilicone elastomer to the shell precursor, applying solid particles of afirst configuration to a portion of the layer of silicone elastomer andapplying solid particles of a second configuration to another portion ofthe layer of silicone elastomer before the layer is fully cured. Afterthe layer including the solid particles embedded therein is cured, thesolid particles are then dissolved, for example, by means of a solventthat does not dissolve the silicone elastomer to any appreciable extent.The resulting elastomer shell includes a first open cell texture regionformed by said application of the solid particles of the firstconfiguration, and a second open cell texture region formed by saidapplication of the solid particles of the second configuration.

One process for forming flexible implant shells for implantableprostheses involves dipping a suitably shaped mandrel into a siliconeelastomer dispersion. Many such dispersions are used in the field.Basically they contain a silicone elastomer and a solvent. The siliconeelastomer is typically polydimethylsiloxane, polydiphenyl-siloxane orsome combination of these two. Typical solvents include xylene or1,1,1-trichloroethane. Different manufacturers vary the type and amountof the ingredients in the dispersion, the viscosity of the dispersionand the solid content of the dispersion. Nonetheless, the presentinvention is expected to be adaptable to have utility with a widevariety of silicone rubber dispersions.

The mandrel is withdrawn from the dispersion and the excess siliconeelastomer dispersion is allowed to drain from the mandrel. After theexcess dispersion has drained from the mandrel at least a portion of thesolvent is allowed to volatilize or evaporate. Normally this isaccomplished by flowing air over the coated mandrel at a controlledtemperature and humidity. Different manufacturers use variousquantities, velocities or directions of air flow and set the temperatureand humidity of the air at different values. However, the desiredresult, driving off the solvent, remains the same.

It is also common for prostheses manufacturers to repeat this dip andvolatilize procedure a number of times so that a number of layers arebuilt up on the mandrel to reach a desired shell thickness. A layeredstructure like most current silicone elastomer shells can be made bysequentially dipping the mandrel in different dispersions.Alternatively, the steps may be repeated in a single dispersion so thatthe finished product is a single homogenous material or layer. That is,the dipping process may be done in multiple stages or steps, each stepadding more material, yet the finished product exhibits no distinctlayers and the entire shell wall is homogenous or uniform incomposition.

An exemplary process for forming the fixation surfaces on either amulti-layered shell or a single-layered shell will now be described.After the mandrel is raised out of the dispersion with what is to be thefinal layer adhering thereto, this layer is allowed to stabilize. Thatis, it is held until the final coating no longer flows freely. Thisoccurs as some of the solvent evaporates from the final coating, raisingits viscosity.

Again, it should be understood that alternative methods are contemplatedfor forming the flexible shell prior to the texturing process. The dipmolding process advantageously results in the flexible shell pre-mountedon a dipping mandrel, which can then be used for the texturing process.However, if the flexible shell is made by another technique, such as byrotational molding, it can subsequently be mounted on a dipping mandreland the process continued in the same manner.

Once the flexible shell has been stabilized and mounted on the mandrel,any loose fibers or particles are removed from the exterior of theshell, for example, with an anti-static air gun. A tack coat layer isthen applied. The tack coat layer may be sprayed on, but is desirablyapplied by dipping the flexible shell on the mandrel into a tack coatdispersion. The operator immerses the flexible shell into the dispersionand returns the mandrel to a rack for stabilization. The time requiredfor stabilization typically varies between 5-20 minutes. A suitable tackcoat layer is desirably made using the same material employed in thebase layers.

At this point, granulated solid particles, for example, dissolvable orleachable particles, are applied over that portion of the exteriorsurface that will end up as the fixation surface. The solid particlesmay be applied manually by sprinkling them over the surface while themandrel is manipulated, or a machine operating like a bead blaster orsand blaster could be used to deliver a steady stream of solid particlesat an adequate velocity to the coating on the mandrel. However, apreferred method of solid particle application is to dip themandrel/shell into a body of the solid particles or expose it to asuspension of the solid particles. It should be understood that thepresent invention is not intended to be restricted to any one particularmethod of applying particles. One possible method to apply solidparticles to some but not all of the shell is to mask off areas of theshell for which particles are not to be applied and then apply theparticles to the non-masked areas.

The tacky flexible shell may then be immersed in a fluidized(air-mixing) aqueous salt bath having regular cubic salt crystalsbetween about 10 to about 600 microns, or round crystals between about50-2000 microns or a combination thereof. Varying degrees of texturingmay be formed with the salt removal process by using differently sizedor shaped salt granules (for example, round salt crystals versus angularsalt crystals, large salt crystals versus relatively small saltcrystals, high density distribution of salt crystals versus relativelylow density distribution of salt crystals), on different areas of theshell. The shell is rotated for even coverage, removed, and then allowedto stabilize. After a suitable period of stabilization, such as betweenabout 5-20 minutes, the flexible shells may be dipped into an overcoatdispersion. A suitable overcoat dispersion may be made using the samematerial employed in the base layers. The flexible shells on themandrels are then mounted on a rack and allowed to volatilize, such as,for example, about 15 minutes.

The entire silicone elastomer shell structure is vulcanized or cured inan oven at elevated temperatures. The temperature of the oven ispreferably kept between about 200° F. and about 350° F. for a curingtime preferably between about 20 minutes and about 1 hour, 40 minutes.Upon removal from the oven, the mandrel/shell assembly is placed in asolvent for the solid particles, and the solid particles allowed todissolve. The solvent does not affect the structure or integrity of thesilicone elastomer. When the solid particles have dissolved, theassembly is removed from the solvent and the solvent evaporated. Theshell can then be stripped from the mandrel. At this point, it ispreferable to place the shell in a solvent for the solid particles andgently agitate it to ensure complete dissolution of all the solidparticles. When the shell is removed from the solvent, the solvent isevaporated.

Dissolving the solid particles leaves behind open, interconnected,cavities in the surface of the shell where the salt had been.

After finishing the shell according to the steps described above, thesteps required to make a finished breast implant prosthesis may besimilar to those known in the art. For example, an opening left by thedip molding process is patched with uncured sheeting, usually made ofsilicone rubber. Then, if the prosthesis is to be filled with siliconegel, this gel is added and cured, the filled prosthesis packaged, andthe packaged prosthesis sterilized. If the prosthesis is to be inflatedwith a saline solution, a one-way valve is assembled and installed, theprosthesis is post cured if required, and the prosthesis is thencleaned, packaged and sterilized. A combination breast implantprosthesis can also be made wherein a gel-filled sac is positionedinside the shell to be surrounded by saline solution.

In addition to the aforementioned dipping process, the flexible shellfor the prosthetic implant may be formed using a molding process. Forexample, a rotational molding process such as described in Schuessler,U.S. Pat. No. 6,602,452 the entire disclosure of which is incorporatedherein, may be used. The process for forming texturing on the exteriorsurface may be done using a dipping technique after the shell is molded,but another method is to roughen the inside of the mold. For example, amold having a generally smooth interior surface except for rough areasas described above will produce an implant shell having discretefixation surfaces. The rotational molding process is advantageousbecause the entire implant shell may be formed in relatively fewmanufacturing steps.

Turning now to FIGS. 9A-9C, another embodiment of the present inventionis illustrated, hereinafter sometimes referred to as a “dual planebreast implant.” FIG. 9A shows a simplified representation of anatomicalplacement of such a breast implant 300, and FIGS. 9B and 9C show a frontview and side view, respectively, of such an implant 300 in accordancewith this embodiment of the invention.

This implant 300 is particularly useful for dual plane breast implantpositioning, such as shown in FIG. 4C. In the dual plane placement ofbreast implants, the upper portion of the implant is covered by musclewhile the lower portion of the implant is not. For example, the implantis positioned such that the upper region of the implant is locatedpartially under and interfacing the pectoralis major muscle 400 (seeFIG. 9A) and a lower region is located in the subglandular plane and notinterfacing muscle tissue.

In one embodiment, the implant 300 generally comprises a relativelytextured lower portion 310, e.g. lower pole, and a relatively smooth orless textured upper portion 314, e.g. upper pole. For example, whenplaced in a “dual plane” position in the breast, the implant 300 of thisembodiment invention may have a stronger binding texture 320 on surfacesof the implant 300 that are in contact with glandular tissue (wheremuscle does not cover/contact the implant 300), and have a less bindingsurface 324 on surfaces of the implant 300 in contact with muscletissue. Although an anatomical, or “teardrop” shaped implant is shown inFIGS. 9A and 9B, it should be appreciated that this dual planeembodiment may comprises other shapes, for example, a “round” shapedimplant, such as shown in FIGS. 1A and 1B.

The lower portion 310 of the exterior surface of the implant 300 mayhave an open-cell textured surface which is designed or structured toprovide enhanced tissue ingrowth and adhesion. The upper portion 312 ofthe exterior surface of the implant may have a smooth surface, a closedcell textured surface, or another surface configuration that isrelatively less aggressive/less conducive to tissue adhesion andingrowth than the texture on the lower portion 310. Many varieties andpermutations are contemplated and are considered to fall within thescope of the invention.

One advantage of this embodiment 300 is that strong tissue adherencewould not be directly associated with attachment to muscle tissue whichmay be more difficult to separate from a strong binding texture. Inaddition, a weak or non-binding surface under the muscle may allow themuscle to slide on the surface of the implant and reduce the tension onthe implant or the movement of the implant with each flexing of themuscle. This embodiment may be particularly advantageous in athleticwoman because it may enhance comfort and the ability to move the musclesof the chest wall while enabling the implant to remain fixed andanchored in the glandular tissue.

In another embodiment of the invention shown in FIGS. 10A and 10B, animplant 400 is provided having a more aggressive texture 412 for strongtissue binding or integration on the anterior surface of the implant400, and therefore fixation of the implant on the anterior portion ofthe implant, and a smooth surface or less textured surface 414 resultingin reduced fixation on the posterior portion of the implant 400. Oneadvantage of this approach is that should the implant 400 need to beremoved, the portion of the implant 400 facing the rib cage can be moreeasily released from the tissue and reduce the potential risks ofsurgical separation of the implant from the tissue in proximity to theribs and plural cavity. Another advantage is that the smooth or lesstextured posterior side of the implant would allow for some movement orsliding of the implant 400, thereby reducing strain on the implantitself when the implant is placed submuscularly or in a dual planeposition where constant flexing of the muscle would potentiallycontinually exert pressure on the implant. This approach would beapplicable to both smooth and shaped implants and would reduce thepotential for rotation. It would also have the added benefit ofpotentially reducing contracture since the texture would still provide adisruption of the alignment of the collagen fibers in any developingcapsule.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the present disclosurehas been made only by way of example, and that numerous changes in thecombination and arrangement of parts can be resorted to by those skilledin the art without departing from the scope of the invention, ashereinafter claimed.

What is claimed is:
 1. A breast implant prosthesis comprising anexterior having a posterior surface, an anterior surface, an upperportion, and a lower portion, the prosthesis having (i) a lower poleregion with a textured outer surface that forms a fixation regionconfigured for subglandular placement and (ii) an upper pole region witha smooth outer surface configured for submuscular placement, a boundarybetween the fixation region and the upper pole region extendingtransverse relative to a vertical axis of the implant prosthesis whenseen in side view, the textured outer surface of the lower pole regionextending along only the lower portion of the exterior, the smooth outersurface of the upper pole region extending along the upper portion ofthe exterior along at least one of the posterior surface or the anteriorsurface of the exterior, the smooth outer surface of the upper poleregion having a texture different from the textured outer surface of thelower pole region.
 2. The prosthesis of claim 1, wherein the texturedouter surface of the lower pole region encompasses between about 20% andabout 80% of the exterior.
 3. The prosthesis of claim 1, wherein thetextured outer surface of the lower pole region encompasses betweenabout 30% and about 70% of the exterior.
 4. The prosthesis of claim 1,wherein the textured outer surface of the lower pole region encompassesbetween about 40% and about 60% of the exterior.
 5. The prosthesis ofclaim 1, wherein the textured outer surface of the lower pole regionencompasses about 50% of the exterior.
 6. The prosthesis of claim 1,wherein the textured outer surface of the lower pole region extendsalong the posterior surface.
 7. The prosthesis of claim 6, wherein thetextured outer surface of the lower pole region further extends alongthe anterior surface.
 8. The prosthesis of claim 1, wherein the texturedouter surface of the lower pole region extends along the anteriorsurface.
 9. The prosthesis of claim 1, wherein the smooth outer surfaceof the upper pole region extends along the posterior surface.
 10. Theprosthesis of claim 9, wherein the smooth outer surface of the upperpole region extends along the anterior surface.
 11. The prosthesis ofclaim 1, wherein the textured outer surface of the lower pole regionouter surface comprises a plurality of textured bands.
 12. Theprosthesis of claim 1, wherein the textured outer surface of the lowerpole region outer surface comprises a plurality of textured bandsextending along an anterior.
 13. A method of augmenting orreconstructing a human breast comprising: implanting in a breast abreast implant including an exterior having a posterior surface, ananterior surface, an upper portion, and a lower portion, the breastimplant having (i) lower pole region with a textured outer surface thatforms a fixation region and (i) upper pole region with a smooth outersurface, the fixation region having an upper edge extending at an anglerelative to a vertical axis of the implant, the textured outer surfaceof the lower pole region extending along only the lower portion of theexterior, the smooth outer surface of the upper pole region extendingalong the upper portion of the exterior along at least one of theposterior surface or the anterior surface of the exterior, the breastimplant being positioned such that the textured outer surface of thelower pole region is placed subglandularly and the smooth outer surfaceof the upper pole region is placed submuscularly.
 14. The method ofclaim 13, wherein the textured outer surface of the lower pole regionencompasses between about 20% and about 80% of the exterior.
 15. Themethod of claim 13, wherein the textured outer surface of the lower poleregion encompasses between about 30% and about 70% of the exterior. 16.The method of claim 13, wherein the textured outer surface of the lowerpole region encompasses between about 40% and about 60% of the exterior.17. The method of claim 13, wherein the textured outer surface of thelower pole region comprises a plurality of textured bands.
 18. Themethod of claim 13, wherein the textured outer surface of the lower poleregion comprises a plurality of textured bands encompassing betweenabout 20% and about 80% of the exterior.
 19. The method of claim 13,wherein the textured outer surface of the lower pole region comprises aplurality of textured bands encompassing between about 30% and about 70%of the exterior.
 20. The method of claim 13, wherein the textured outersurface of the lower pole region comprises a plurality of textured bandsencompassing between about 40% and about 60% of the exterior.